Chang Chung, PE, a Senior Structural Engineer in McCormick Taylor’s Mount Laurel office, discussed the Garden State Parkway (GSP) Culvert Repair Project at Milepost 118 during the American Society of Civil Engineers’ (ASCE) Central Jersey Branch dinner on September 20. He covered the project’s uniqueness and McCormick Taylor’s experience as it relates to the professional engineering community. In addition to construction challenges and solutions, the presentation gave an overview of alternative analysis to handle hydraulic capacity of the culvert and structural challenges to accommodate the preferred alternative.

McCormick Taylor completed final design for the repair of twin corrugated metal plate arch culverts in risk of collapse at milepost 118.5 on the GSP. These major storm drainage culverts convey Lopatcong Creek through the GSP in Hazlet Township, Monmouth County, New Jersey and exhibited signs of advanced and extensive deterioration.

The invert of culvert #1 deflected 2.5 feet from the time McCormick Taylor first inspected the site in December 2010 to the time of construction in April 2012, a period of just 16 months. McCormick Taylor worked with the contractor, Northeast Remsco, to develop a temporary support system to stabilize the culvert while the deflected sections were cut out and the new lining system was constructed.

In culvert #1, deficiencies included failure of the structural plate, heave of the longitudinal bolted invert joint, separation of one of the circumferential joints, significant section loss in the lower half of the pipe, and a sagging crown with vertical displacement. In culvert #2, the invert had heaved and the crown sagged significantly along one quarter of the length, reducing the height of the culvert.

The selection of the preferred alternative was driven by accommodating the significant deflection of the culverts, maintaining the maximum hydraulic capacity, and providing a structural system capable of carrying the loads applied by 30 feet of overburden. McCormick Taylor chose a traditional tunnel lining concept as the preferred rehabilitation concept. Using information derived from a detailed laser survey of the interiors of both culverts, McCormick Taylor designed structural steel ribs, intermediate reinforcing steel, and shotcrete to form a robust interior lining.